Study on the long-distance settlement threshold of high-speed railway subgrade based on vehicle responses

The long-distance and large-scale subgrade settlement is a key issue in high-speed railway (HSR). This work focuses on the long-distance settlement threshold for the HSR subgrade. A Green's function-based hybrid dynamic model with high efficiency is established to achieve the long-distance analysis of the vehicle-track-subgrade interaction system with a wide range of subgrade settlement. Based on the analysis results, the Wavelet decomposition technique is applied to extract the low-frequency components of vehicle responses excited by the additional deformation of rails induced by the long-distance subgrade settlement. The simulation results show that the low-frequency vibrations of vehicle are mainly excited by the additional deformation of rails induced by settlement. Based on the correlation between the vehicle responses and the second derivative of additional deformation of rails, the threshold of long-distance settlement can be determined. The vehicle response and subgrade settlement signal are linked in the time-frequency domain, and the relationship between system excitation and response is clearly revealed. This paper provides a referenceable analysis framework that is convenient for engineers in the control for the amplitude of large-scale subgrade settlement in HSR.